Reviews: Learning Sparse Gaussian Graphical Models with Overlapping Blocks

In this framework, the entries in Z are within [-1, 1]. In the context of stochastic block model, there is also an assignment matrix Z with entries {0, 1} (see Rohe et al 2011 Spectral clustering and the high-dimensional stochastic blockmodel). How does Z here (in the special binary case) compare with the Z matrix in Rohe et al. 2011? Why is it not allowed for all variables to be assigned to one block? It's possible that one wants to analyze the interaction network among genes from the same pathway (the same block).